﻿// ConsoleTools
// Copyright (C) 2017-2024 Dust in the Wind
// 
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
// 
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
// 
// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

// --------------------------------------------------------------------------------
// Bugs or feature requests
// --------------------------------------------------------------------------------
// Note: For any bug or feature request please add a new issue on GitHub: https://github.com/lastunicorn/ConsoleTools/issues/new/choose

using System;
using System.ComponentModel;

namespace DustInTheWind.ConsoleTools.Controls.Menus.MenuItems;

/// <summary>
/// Represents a menu item that displays a text.
/// </summary>
public class LabelMenuItem : IMenuItem
{
    private const HorizontalAlignment DefaultHorizontalAlignment = HorizontalAlignment.Center;

    private bool isVisible = true;
    private bool isEnabled = true;

    /// <summary>
    /// Gets the location in the console where the current instance was last rendered.
    /// If the current instance was never rendered, this value is <c>null</c>.
    /// </summary>
    public Location? Location { get; private set; }

    /// <summary>
    /// Gets the size in characters necessary for the current instance to be rendered.
    /// </summary>
    public Size Size
    {
        get
        {
            int width = PaddingLeft + (Text?.Length ?? 0) + PaddingRight;
            int height = 1;

            return new Size(width, height);
        }
    }

    /// <summary>
    /// Gets or sets the text displayed by the current instance.
    /// </summary>
    public string Text { get; set; }

    /// <summary>
    /// Gets or sets a value that specifies if the current instance is displayed.
    /// If the <see cref="VisibilityProvider"/> is set, the value provided on the setter,
    /// is ignored.
    /// </summary>
    public bool IsVisible
    {
        get => VisibilityProvider?.Invoke() ?? isVisible;
        set => isVisible = value;
    }

    /// <summary>
    /// Gets or sets a function that specifies if the current instance should be visible.
    /// </summary>
    public Func<bool> VisibilityProvider { get; set; }

    /// <summary>
    /// Gets or sets the horizontal alignment of the current instance inside the menu.
    /// Default value: <see cref="Controls.HorizontalAlignment.Default"/>.
    /// </summary>
    public HorizontalAlignment HorizontalAlignment { get; set; } = HorizontalAlignment.Default;

    /// <summary>
    /// Gets a value that specifies if the current instance can be selected.
    /// Default value: <c>true</c>
    /// </summary>
    public bool IsEnabled
    {
        get => Command?.IsActive ?? isEnabled;
        set => isEnabled = value;
    }

    /// <summary>
    /// Gets or sets the shortcut key that will select the current instance of <see cref="IMenuItem"/>.
    /// Default value: <c>null</c>
    /// </summary>
    public ConsoleKey? ShortcutKey { get; set; }

    /// <summary>
    /// Gets or sets the command to be executed when the current instance is selected.
    /// Default value: <c>null</c>
    /// </summary>
    public ICommand Command { get; set; }

    /// <summary>
    /// Gets or sets the menu that contains the current instance.
    /// Default value: <c>null</c>
    /// </summary>
    public ScrollMenu ParentMenu { get; set; }

    /// <summary>
    /// Gets or sets the padding applied to the left of the text.
    /// The padding is part of the menu item's width.
    /// Default value: 1
    /// </summary>
    public int PaddingLeft { get; set; } = 1;

    /// <summary>
    /// Gets or sets the padding applied to the right of the text.
    /// The padding is part of the menu item's width.
    /// Default value: 1
    /// </summary>
    public int PaddingRight { get; set; } = 1;

    /// <summary>
    /// Event raised before the current instance is selected.
    /// It gives the opportunity for a subscriber to cancel the selection of the menu item.
    /// </summary>
    public event EventHandler<CancelEventArgs> BeforeSelect;

    /// <summary>
    /// Displays the current instance to the Console starting from the current location of the cursor.
    /// </summary>
    /// <param name="size">The size in which the current instance must be displayed.</param>
    /// <param name="highlighted">A value that specifies if the menu item must be displayed highlighted.</param>
    public void Display(Size size, bool highlighted)
    {
        HorizontalAlignment calculatedHorizontalAlignment = CalculateHorizontalAlignment();

        Location = new Location(Console.CursorLeft, Console.CursorTop);

        AlignedText alignedText = new()
        {
            Text = new string(' ', Size.Width),
            HorizontalAlignment = calculatedHorizontalAlignment,
            Width = size.Width
        };

        // Write left empty space
        CustomConsole.Write(new string(' ', alignedText.SpaceLeftCount));

        // Write content
        if (highlighted)
            CustomConsole.WithInvertedColors(DisplayContent);
        else
            DisplayContent();

        // Write right empty space
        CustomConsole.Write(new string(' ', alignedText.SpaceRightCount));
    }

    private void DisplayContent()
    {
        // Write left padding
        if (PaddingLeft > 0)
            CustomConsole.Write(new string(' ', PaddingLeft));

        // Write the text
        CustomConsole.Write(Text);

        // Write right padding
        if (PaddingRight > 0)
            CustomConsole.Write(new string(' ', PaddingRight));
    }

    private HorizontalAlignment CalculateHorizontalAlignment()
    {
        if (HorizontalAlignment != HorizontalAlignment.Default)
            return HorizontalAlignment;

        if (ParentMenu != null && ParentMenu.ItemsHorizontalAlignment != HorizontalAlignment.Default)
            return ParentMenu.ItemsHorizontalAlignment;

        return DefaultHorizontalAlignment;
    }

    /// <summary>
    /// Selects the current instance and executes the associated <see cref="Command"/>.
    /// </summary>
    /// <returns><c>true</c> if the menu item was successfully selected; <c>false</c> otherwise.</returns>
    public bool Select()
    {
        CancelEventArgs eventArgs = new();
        OnBeforeSelect(eventArgs);

        return !eventArgs.Cancel;
    }

    /// <summary>
    /// Raises the <see cref="BeforeSelect"/> event.
    /// </summary>
    protected virtual void OnBeforeSelect(CancelEventArgs e)
    {
        BeforeSelect?.Invoke(this, e);
    }
}